20979805 has 16 divisors (see below), whose sum is σ = 31388544. Its totient is φ = 13078080.

The previous prime is 20979799. The next prime is 20979809. The reversal of 20979805 is 50897902.

It is not a de Polignac number, because 20979805 - 2⁷ = 20979677 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20979809) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 26862 + ... + 27631.

It is an arithmetic number, because the mean of its divisors is an integer number (1961784).

Almost surely, 2^20979805 is an apocalyptic number.

It is an amenable number.

20979805 is a deficient number, since it is larger than the sum of its proper divisors (10408739).

20979805 is a wasteful number, since it uses less digits than its factorization.

20979805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54516.

The product of its (nonzero) digits is 45360, while the sum is 40.

The square root of 20979805 is about 4580.3717098070. The cubic root of 20979805 is about 275.8039504262.

The spelling of 20979805 in words is "twenty million, nine hundred seventy-nine thousand, eight hundred five".